The apparatus in accordance with the invention relates to removal of ice which has accumulated on antennas as well as for preventing the formation of ice on antennas. The apparatus has particular application to large earth station antennas for communications applications utilizing satellites. In a typical antenna installation there may be two dish shaped antennas having a diameter of approximately ten meters. Such antennas may cooperate with satellites and may have, for example, approximately 144 voice and data circuits. A problem with the utilization of such antennas is that signal distortions occur when ice accumulates on such antennas. The formation of ice may also reduce the strength of the signal which is taken from the antenna. The difficulty of preventing ice formation is particularly acute because of the large surface area of the antennas (e.g. the area may be about 845 square feet) and such antennas are typically installed at high elevations where the climate may be most conducive to the formation of ice.
The prior art apparatus for prevention and removal of ice formations includes the use of electrical resistance tape or pad assemblies. Such apparatus has been found to be expensive to purchase, to install, and to operate. Typically such tapes or pads have been installed on the lower extremity of the antenna. This has tended to cause distortion of the signal or signals received by the antenna. Hot air heating systems have also been used in which the lower half of the antenna was enclosed and warm air was pumped by a tube into the bottom of the antenna and then passed out of the top of the enclosure. These known apparatus have not been wholly satisfactory either because of the cost of initial aquisition, installation, or operation, or because they did not produce the desired result. Some antennas which do not have any ice control apparatus and also some antennas which were nominally provided with such apparatus have experienced a significant amount of down time because of such ice formation.
It is a primary object of the invention to provide apparatus which will reduce the down time of the antenna with which it cooperates.
It is another object of the invention to provide apparatus which will avoid signal loss or distortion due to ice formation.
It is another object of the invention to provide apparatus which will not inherently result in signal distortion due to the electo-magnetic characteristics of the apparatus.
It is another object of the invention to provide apparatus which will have a small power consumption and thus low operating cost.
It is another object of the invention to provide apparatus which will improve the aesthetic appearance of an earth station antenna.
It is still another object of the invention to provide apparatus which will avoid unnecessary operation of the ice control apparatus in accordance with the invention.
It is yet another object of the invention to provide apparatus which may be installed without interruption of the operation of the antenna with which it cooperates.
Yet another object of the invention is to provide apparatus which will be capable of burning a wide variety of fuels so that the apparatus may function with a fuel which is most readily available in the region in which the apparatus will function.